5-Aminotetrazole
{{Chembox
| ImageFile = Aminotetrazole.png
| ImageSize = 120px
| ImageAlt =
| ImageFile2 = 5-amino-1H-tetrazole.jpg
| PIN = 1H-1,2,3,4-Tetrazol-5-amine
| OtherNames = 5-ATZ
| Section1 = {{Chembox Identifiers
| CASNo = 4418-61-5
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 28JR5LD42T
| PubChem = 20467
| ChemSpiderID = 19274
| SMILES = c1([nH]nnn1)N
| InChI = 1/CH3N5/c2-1-3-5-6-4-1/h(H3,2,3,4,5,6)
| InChIKey = ULRPISSMEBPJLN-UHFFFAOYAD
| StdInChI = 1S/CH3N5/c2-1-3-5-6-4-1/h(H3,2,3,4,5,6)
| StdInChIKey = ULRPISSMEBPJLN-UHFFFAOYSA-N }}
| Section2 = {{Chembox Properties
| C=1 | H=3 | N=5
| Appearance = White solid
| Density = 1.502 g/cm3
| MeltingPtC = 201-205
| BoilingPt =
| Solubility = }}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
|GHSPictograms = {{GHS02}}{{GHS corrosion}}}}
| Section4 =
}}
5-Aminotetrazole is an organic compound with the formula HN4CNH2. It is a white solid that can be obtained both in anhydrous and hydrated forms.
The molecule is planar.Hiroshi Fujihisa, Kazumasa Honda, Shigeaki Obata, Hiroshi Yamawaki, Satoshi Takeya, Yoshito Gotoha, Takehiro Matsunaga "Crystal structure of anhydrous 5-aminotetrazole and its high-pressure behavior" CrystEngComm, 2011, volume 13, pp. 99-102. {{doi|10.1039/C0CE00278J}} The hydrogen bonding pattern in the hydrate supports the assignment of NH being adjacent to carbon in the ring.D. D. Bray and J. G. White "Refinement of the structure of 5-aminotetrazole monohydrate" Acta Crystallogr. (1979). B35, pp. 3089-3091.{{doi|10.1107/S0567740879011493}}
Preparation
A synthesis of 5-aminotetrazole through the action of nitrous acid on aminoguanidine was reported by Johannes Thiele in 1892.{{cite journal|last=Thiele|first=Johannes|date=1892-01-01|title=Ueber Nitro- und Amidoguanidin|journal=Justus Liebigs Annalen der Chemie|volume=270|issue=1–2|pages=1–63|doi=10.1002/jlac.18922700102|issn=0075-4617|url=https://zenodo.org/record/1427445}}
The exact structure of the compound was not known at the time, although it was known to crystallize as a monohydrate. The correct structural formula was published in 1901 by Arthur Hantzsch, who obtained it from the reaction between cyanamide and hydrazoic acid.{{cite journal|last1=Hantzsch|first1=A.|last2=Vagt|first2=A.|date=1901-01-01|title=Ueber das sogenannte Diazoguanidin|journal=Justus Liebigs Annalen der Chemie|volume=314|issue=3|pages=339–369|doi=10.1002/jlac.19013140307|issn=0075-4617|url=https://zenodo.org/record/1427523}}
:File:5-Aminotetrazol_Synthese_aus_Cyanamid.svg
To avoid direct handling of the problematic hydrazoic acid, a mixture of sodium azide and hydrochloric acid has been used to give the monohydrate at 73% yield.{{cite journal|last1=MIHINA|first1=JOSEPH S.|last2=HERBST|first2=ROBERT M.|title=The Reaction of Nitriles with Hydrazoic Acid: Synthesis of Monosubstituted Tetrazoles|date=1950-09-01|journal=The Journal of Organic Chemistry|volume=15|issue=5|pages=1082–1092|doi=10.1021/jo01151a027|issn=0022-3263}}
:File:5-Aminotetrazol_Synthese_aus_Dicyandiamid.svg
In a more efficient and controllable one-pot synthesis, cyanamide is treated with hydrazine hydrochloride to give aminoguanidine hydrochloride, which is then diazotized as in Thiele's original process. Addition of ammonia or sodium hydroxide followed by heat-induced cyclization gives the anhydrous product in 74% yield.{{cite patent|country=US|number=5424449|title=Process for the preparation of 5-aminotetrazole|status=|pubdate=1995-06-13|gdate=1995-06-13|invent1=Rothgery|invent2=Knollmueller|inventor1-first=Eugene F.|inventor2-first=Karl O.}}{{cite patent|country=US|number=5594146|title=Process for producing 5-aminotetrazole|status=|pubdate=1997-01-14|gdate=1997-01-14|invent1=Murotani|invent2=Mura|invent3=Takeda|invent4=Shibafuchi|inventor1-first=Masahiro|inventor2-first=Hajime|inventor3-first=Makoto|inventor4-first=Hiroshi}}
Structure
The structure of 5-aminotetrazole has been determined several times by X-ray crystallography, both as the anhydrous{{cite journal |doi=10.1039/c0ce00278j|title=Crystal structure of anhydrous 5-aminotetrazole and its high-pressure behavior |year=2011 |last1=Fujihisa |first1=Hiroshi |last2=Honda |first2=Kazumasa |last3=Obata |first3=Shigeaki |last4=Yamawaki |first4=Hiroshi |last5=Takeya |first5=Satoshi |last6=Gotoh |first6=Yoshito |last7=Matsunaga |first7=Takehiro |journal=CrystEngComm |volume=13 |pages=99–102 }} and monohydrated forms.{{cite journal |doi=10.1107/S0567740879011493|title=Refinement of the structure of 5-aminotetrazole monohydrate |year=1979 |last1=Bray |first1=D. D. |last2=White |first2=J. G. |journal=Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry |volume=35 |issue=12 |pages=3089–3091 |bibcode=1979AcCrB..35.3089B }} The structures are very similar, consisting of a planar molecule, including the amino group.
Uses
5-Aminotetrazole has found applications in heterocyclic chemistry, particularly as a synthon for some multicomponent reactions.{{cite journal|last=Dolzhenko|first=A. V.|date=2017|title=5-Aminotetrazole as a Building Block for Multicomponent Reactions (Review)|url=http://www.heterocycles.jp/newlibrary/libraries/abst/25419|journal=Heterocycles|language=en|volume=94|issue=10|pages=1819–1846|doi=10.3987/rev-17-867|doi-access=free}}
The N-4 is basic as indicated by its binding to metal halides, such as the coordination complex {{chem2|[CoCl2(aminotetrazole)4}}.{{cite journal |doi=10.1021/ic300394c|title=Two Acentric Mononuclear Molecular Complexes with Unusual Magnetic and Ferroelectric Properties |year=2012 |last1=Zhao |first1=Fang-Hua |last2=Che |first2=Yun-Xia |last3=Zheng |first3=Ji-Min |last4=Grandjean |first4=Fernande |last5=Long |first5=Gary J. |journal=Inorganic Chemistry |volume=51 |issue=8 |pages=4862–4868 |pmid=22480292 }}
The compound has a particularly high nitrogen content of 80%. Partly for this reason, the compound is prone to decomposition to nitrogen gas (N2). It has been widely investigated for gas-generating systems, such as airbags and blowing agents.Lesnikovich, A. I.; Ivashkevich, O. A.; Levchik, S. V.; Balabanovich, A. I.; Gaponik, P. N.; Kulak, A. A. "Thermal decomposition of aminotetrazoles" Thermochimica Acta 2002, vol. 388, pp. 233-251. {{doi|10.1016/S0040-6031(02)00027-8}}